A Molecular Brush Approach to Enhance Quantum Yield and Suppress Nonspecific Interactions of Conjugated Polyelectrolyte for Targeted Far-Red/Near-Infrared Fluorescence Cell Imaging

Authors

  • Kan-Yi Pu,

    1. Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, 117576 (Singapore)
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  • Kai Li,

    1. Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, 117576 (Singapore)
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  • Bin Liu

    Corresponding author
    1. Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, 117576 (Singapore)
    • Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, 117576 (Singapore).
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Abstract

A red-fluorescent conjugated polyelectrolyte (CPE, P2) is grafted with dense poly(ethylene glycol) (PEG) chains via click chemistry and subsequently modified with folic acid to form a molecular brush based cellular probe (P4). P4 self-assembles into a core–shell nanostructure in aqueous medium with an average size of 130 nm measured by laser light scattering. As compared to P2, P4 possesses not only a substantially higher quantum yield (11%), but also reduced nonspecific interactions with biomolecules in aqueous medium due to the shielding effect of PEG. In conjunction with its high photostability and low cytotoxicity, utilization of P4 as a far-red/near-infrared cellular probe allows for effective visualization and discrimination of MCF-7 cancer cells from NIH-3T3 normal cells in a high contrast, selective, and nonviral manner. This study thus demonstrates a flexible molecular brush approach to overcome the intrinsic drawbacks of CPEs for advanced bioimaging applications.

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